898 research outputs found

    The prescribed Ricci curvature problem for naturally reductive metrics on compact Lie groups

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    We study the problem of prescribing the Ricci curvature in the class of naturally reductive metrics on a compact Lie group. We derive necessary as well as sufficient conditions for the solvability of the equations and provide a series of examples.Comment: 13 pages, 5 figure

    Solidifying system of democracy in the Central and Eastern European new EU members

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    The paper examines the requirements of an effective and legitimized democratic political system in the process of transition. The analysis and the conclusions are based on the Hungarian experience, which can carefully be applied to all Central and Eastern European (CEE) countries. Special focus is given to the relationship of legal certainty and the efficiency of the democratic system, to the tension between legalism and managerialism and to the characteristics of civil society organizations. In the conclusion special features of the transitional countries are pointed out

    A Bayesian Model for Spatial Disease Prevalence Data

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    The analysis of the geographical distribution of disease on the scale of geographic areas such as administrative boundaries plays an important role in veterinary epidemiology. Prevalence estimates of wildlife population surveys are often based on regional count data generated by sampling animals shot by hunters. The observed disease rate per spatial unit is not a useful estimate of the underlying disease prevalence due to different sample sizes and spatial dependencies between neighbouring areas. Therefore, it is necessary to account for extra-sample variation and and spatial correlation in the data to produce more accurate maps of disease incidence. For this purpose a hierarchical Bayesian model in which structured and un-structured overdispersion is modelled explicitly in terms of spatial and non-spatial components was implemented by Markov Chain Monte Carlo methods. The model was empirically compared with the results of the non-spatial beta-binomial model using surveillance data of Pseudorabies virus infections of wildboars in the Federal State of Brandenburg, Germany

    Nonnegatively curved homogeneous metrics obtained by scaling fibers of submersions

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    We consider invariant Riemannian metrics on compact homogeneous spaces G/H where an intermediate subgroup K between G and H exists, so that the homogeneous space G/H is the total space of a Riemannian submersion. We study the question as to whether enlarging the fibers of the submersion by a constant scaling factor retains the nonnegative curvature in the case that the deformation starts at a normal homogeneous metric. We classify triples of groups (H,K,G) where nonnegative curvature is maintained for small deformations, using a criterion proved by Schwachh\"ofer and Tapp. We obtain a complete classification in case the subgroup H has full rank and an almost complete classification in the case of regular subgroups.Comment: 23 pages; minor revisions, to appear in Geometriae Dedicat

    On the terms violating the custodial symmetry in multi-Higgs-doublet models

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    We prove that a generic multi-Higgs-doublet model (NHDM) generally must contain terms in the potential that violate the custodial symmetry. This is done by showing that the O(4) violating terms of the NHDM potential cannot be excluded by imposing a symmetry on the NHDM Lagrangian. Hence we expect higher-order corrections to necessarily introduce such terms. We also note, in the case of custodially symmetric Higgs-quark couplings, that vacuum alignment will lead to up-down mass degeneration; this is not true if the vacua are not aligned.Comment: 16 pages, 1 figure. Title and abstract are modified, conclusions remain the same. Section on Yukawa couplings is extended. Published versio

    The Tetramethylpiperidinyl-1-Oxide Anion (TMPO-) as a Ligand in Lanthanide Chemistry: Synthesis of the Per(TMPO-) Complex [(ONC5H6Me4)2Sm(μ-ONC5H6Me4)]2

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    (C5Me5)3Sm reacts with the free radical 2,2,6,6-tetramethylpiperidinyl-1-oxy (TMPO) to form (C5Me5)2 and the per nitroxide [(η1-ONC5H6Me4)2 Sm(μ-η1∶η2-ONC5H 6Me4)]

    Impact of Employment Transitions on Health Insurance Coverage of Rural Residents

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    Numerous studies have found that rural residents are more likely to be uninsured than urban residents. This coverage difference is generally due to more limited access for rural workers to employer-sponsored health insurance. Lower wages, and the tendency for rural residents to work for small employers, account for this reduced access. While we have substantial information on static insurance coverage rates for rural residents, our knowledge about how coverage changes with employment transitions is limited. Prior research indicates that loss of a job puts workers at greater risk of becoming uninsured, and there is some evidence that this risk is even greater for rural workers. Other studies suggest that access to health insurance plays an important role in determining whether a worker decides to change. Whether this relationship is any different for urban versus rural workers has not been well-studied. In the past 20 years, much of the federal-level policy attention related to health insurance coverage has emphasized ensuring continuity of coverage for individuals that experience an employment transition. For example, the Consolidated Omnibus Budget Reconciliation Act (COBRA), passed in 1985, ensured that those with employer-sponsored coverage could retain that coverage even if that employment ceased. Similarly, the 1996 Health Insurance Portability and Accountability Act (HIPAA) guaranteed individual coverage for those who leave a group plan. However, both of these key policy interventions are inapplicable to the smaller employers that are the backbone of rural economies. Thus, rural workers may be more likely than urban workers to experience disruptions in health insurance coverage following an employment transition. The Patient Protection and Affordable Care Act (ACA) provides a new background against which to consider the issues of job change, job loss, health insurance portability and coverage of rural residents. Understanding how changes in employment status impact insurance coverage for rural workers can help to identify potential challenges and opportunities for implementing ACA in rural areas
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